Radiantly heated rotary carrier for destructive distillation



Dec. l2, 1950 2,533,492

L. A. MEKLER RADIANTLY HEATED ROTARY CARRIER lFOR DESTRUCTIVEDISTILLATION Filed Marh 19, 1947 5 Sheets-Sheet l Dec. l2, 1950 L. A.MEKLER 2,533,492

RADIANTLY HEATED ROTARY CARRIER FOR DESTRUCTIVE DISTILLATION Filed March19, 194'? 3 Sheets-Sheet 2 Dec. l2, 1950 L. A. MEKLER 2,533,492

RADIANTLY HRATED ROTARY CARRIER RoR DESTRUCTIVE DISTILLATION Filed March19, 1947 5 Sheets-Sheet 3 Paume D. 12, leso UNITED s'rArEs yPATENTorrlcE RDIANTLY HEATED ROTARY CARRIER FOB DESTBUCTIVE DISTILLATIOIF LevA. Mekler, Chicago, Ill., assigner to Institute of Gas Technology,Chicago, lll., a corporation of Illinois sneeuw man 1a. im, serial No.135,111

,such as coal, lignin, oil shale; vegetable matter and the like.

In some of the hightemperature coking processes presently employed forthel coking of heavy oils, a pool of oil is poured on the floor of achamber heated from below by the combustion of fuel in subjacent nues,the heat required for carbonization being conducted upwardly throughsaid iloor. After a nrst pool of oil has been coked, a second pool ofoil is poured onto the coke formed from the nrst pool. I'he heatrequired for carbonization of the second pool is supplied to the poolthrough the iioor of the earbonization chamber and through the iirstlayer of coke formed from the ilrst pool. This process is repeated untila layer of coke of suitable thickness has been formed on the floor ofthe chamber. With each successive layer of coke formed, the temperatureinside the tlues is progressively raised so that each layer of cokebelow the uppermost layer is subjected to increasingly highertemperatures for increasingly longer periods of time. As av result,

Vthe various layers of coke formed on the bottom of the chamber aredistinguished by widely variant characteristics, as are also the gaseousproducts obtained in the coking of the various pools of oil. I

In this connection, it should be understood that heavy oils and the likeare coked by subjecting the oils to an elevated .temperature for asuflicient time to decompose'the oils into gas,

light, intermediate and heavy distillates, an'd coke temperatures arenormally a mixture of parai'iins: and/or oleiins with very small amountsof aro` matics. When petroleum still residues are coked at temperaturesabove 1200" F. and particularly at temperatures'between 1400 F. and l800F., the yield of distillates is considerably lreduced. the amount of gasproduced and the mount o! 4 Claims. (Cl. 1R02- 117) aromatica in thegases and in the distillate is increased while the volatile matter inthe coke is reduced to as little as 0.5%. particularly if sutilcienttime is allowed to dry the coke and tn crack the constituents of thevolatile matter. It

is therefore clear that, while time and temperature can be variedinversely to some extent so that overall quantitative results can beobtained at lower temperatures maintained for a relatively long time orhigher temperatures maintained for a shorter time. yet the quality ofthe gases, the distillates and the coke produced are determined by thespecic temperature and the time during which this temperature is appliedto the material undergoing treatment.

Hence, to produce carbonaceous material of uniform quality consistently,it is necessary to subject all the material being treated toapproximately the same temperature for the same period of time. Asexplained hereinabove, this result cannot be achieved when the heat forthe destructive distillation is supplied through the iloor of thedistillation chamber and several layers of oil are successively coked onthe oor and the resulting layers of coke are not removed but are allowedto accumulate.

It has therefore been proposed to eil'ect transmission of heat to alayer of oil or the like to be carbonized by downward radiation from asource of heat arranged at or near the top of the distillation chamber.However, with such an arrangement, the gases generated duringdestructive distillation rise and contact said source of heat, beingcracked or carbonized with resultant deposition of carbon on the sourceof heat. In the destructive distillation of heavy oils or the likeinvolving transmission of heat by radiation from above, the removal ofcarbon deposits from the source of radiant heat has therefore presenteda difllcult problem.

I have now provided an improved apparatus and method for destructivedistillation involving the transmission of heat to the material beingdistilled from above by radiation from hollow bodies supplied with airand fuel for internal combustion in said bodies; The latter areconstructed of material characterized by a relatively high coemcient ofexpansion, so that when coke or carbon has been deposited on said bodiesby the cracking of gaseous products oi distillation, internal combustionin said bodies can be terminated and the bodies allowed to cool (as bycontinued blowing of air alone through said bodies) with resultantcontraction of said bodies and shearing or cracking of carbon adheringthereto.

It is. therefore, an important object of the present invention toprovide method and apparatus for destructive distillation involving thetransmission of heat by radiation from above to the material beingdistilled, the source of heat being an internally fired body exposed tocontact with the gases generated during distillation and characterizedby a relatively high coeillcient of expansion so that carbon depositedthereon due to contact therewith of said gases can be cracked or shearedoff from said body by cooling thereof.

A specific object of the invention is to provide an apparatus of thenature indicated capable of continuous operation.

Other and lfurther objects and features of the present invention willbecome apparent from the following description and the accompanyingdrawings showing, diagrammatically and by way of example, three types ofapparatus according to the present invention taken in conjunction withthe appended claims. More particularly, in the drawings:

Figure 1 is a transverse cross sectional view, with parts shown inelevation, of a furnace according to the present invention;

Figure 2 is a fragmentary longitudinal vertical cross sectional viewtaken along the line II-II of Figure 1;

Figure 3 is a fragmentary transverse cross sectional view, with partsshown in elevation, of a furnace generally similar to that shown in Fig.1 but including combustion tubes mounted in a different manner;

Figure 4 is a plan View, with parts shown in horizontal section, ofanother furnace according to the present invention;

Figure 5 is a vertical cross sectional view taken along the line VV ofFig. 4, with parts shown in elevation and other parts broken away; and

Figure 6 is a vertical cross sectional view taken along the line VI--VIof Fig. 4, with parts broken away and other parts shown in elevation.

In Figures 1 and 2, the reference numeral I0 indicates generally adistillation furnace according to the present invention of generallyrectangular vertical cross section formed with an internal cokingchamber II dened by a coking floor I2. vertical side walls I3 and a roofI4, all preferably made of relatively non-porous refractory material ofrelatively low he'at conductivity. The refractory material is insulatedon the outside with suitable insulating material I6, to conserve heatand to maintain the coking chamber at substantially uniform temperature.The coking chamber is maintained at the desired temperature by means ofheat radiating burner tubes I1 piercing the side walls and suspendednear the roof Il by means of a plurality oi' metal bars I8 extendinglongitudinally within the coking chamber and suspended by other bars I9depending from the roof. Oil to be cokedv is injected into the cokingchamber through nozzles 20 extending through the side walls.

The tubes I1 are made of material charac@ terized by high heatconductivity and a relatively high coefficient of expansion, such assuitable ceramic material or, preferably, stainless steel, or otheraustenitic iron alloys, to reduce to a minimum the temperaturedifference between the inside of the tube and the temperature in thecoking chamber and to bring about maximum expansion of the tube onheating followed by maximum contraction on subsequent cooling. A uidfuel is supplied to one end of the tube I1 (outside of furnace I0)through a valved conduit 2| and air under pressure through a valvedconduit 22 joining the conduit 2| before the latter enters the end ofthe tube I1. The other end of the tube I1 discharges combustion gasesinto a flue or header 23.

In operation of the furnace I0 shown in Figs. 1 and 2, a thin layer ofgranular or finely divided coke of the type obtained by the operation ofsaid furnace is initially spread over the oor I2 of the chamber II toform a zone of cleavage between the coke subsequently produced in thefurnace and the floor of the furnace, whereby the removal of the cokefrom the chamber at the end of the operating cycle is facilitated. Thechamber II is next raised to the desired temperature (above 1200" F. andpreferably from 1400 to 1800 F. in the coking of petroleum stillresidues) by combustion of the required amount of uid and air in thecombustion tubes l1. A predetermined amount of tar or petroleum stillresidue or the like is next introduced into the chamber Il through thenozzles 20 to form -a relatively shallow pool on the floor I2 of thechamber where the material remains until coked by the heat radiated fromthe combustion tubes I1. When the first charge has been coked to form alayer of coke from 1A inch to 1 inch thick, a second charge ofsubstantially the same quantity as the first charge is admitted to thechamber II to form a second pool on top of the coke formed from thefirst charge. This operation is repeated with as-many subsequent chargesof material as is necessary to form a slab of coke of desired thickness,say, from 1 to 6 inches. In this slab of coke, each layer is formedunder substantially identical temperature conditions maintained forsubstantially the same length of time. The slab is therefore of uniformquality throughout.

As each pool of residue or tar or the like is being coked, the gases andvapors then generated rise from the pool towards the roof I4 of thechamber II, come in contact with the surfaces of the tubes I1 heated byinternal combustion and are cracked on these surfaces to form a layer ofcoke on the tube surfaces. This layer of coke, if permitted to remain onthe tubes, would act as an insulator with the result that thetemperature of the chamber would be lowered if the temperature ismaintained constant within the combustion tubes, or the internalcombustion temperatures would have to be raised to maintain a constantchamber temperature. In order to maintain a uniform coking temperaturewithout any necessity for raising the internal combustion tubetemperature, the coke is periodically cracked off from the combustiontubes I1 by periodically interrupting the flow of fuel to the interiorof the tubes without interrupting the air supply to the interior of thetubes. Thus, the tubes I 1 are suddenly chilled from time to time. Thecontraction of the tubes on such chilling cracks oif the carbondeposited on the tubes, surface to reestablish the desired relationshipbetween the tube ternperature and the chamber temperature. When fuel isagain admitted to the tubes, the expansion of the tubes on being heatedwill serve to crack off whatever coke may remain on the tubes at' theend of the contraction of the tubes. The coke cracked off from the tubesI1 falls on top of the layer being coked and is incorporated in thefinal slab of coke by the coking of a. subsequent charge of oil or thelike.

Some oils .tend to foam when coked. This foaming can be materiallyreduced by introducassassin ing relatively small amounts, up to of thecoke being produced, of granulated coke over the flow and over the topsof the coke bedsbefore introducing each charge of oil. Said introductionof coke also serves to increase the density of the coke produced, whichsometimes is desirable, par. ticularly if the amount of the coke crackedon the tubes I'I is not sumcient to serve this purpose.

The frequency of chilling and reheating of the tubes Il to keep thesetubes clean enough for elllcient operation is determined by the rate offormation of gases and vapors contacting the tubes and on the cokeforming characteristics of these gases and vapors. The chilling andreheating cycle can be started automatically by thermostatic means (notshown) controlled by the temperature of the metal of the tubes, by thetemperature of the gases discharged from the tubes into the exhaustheader 23, or by any other suitable means. so that the desired chambertemperature is automatically maintained during the whole cokingoperation.

In Fig. 3 I have shown another furnace l0 according to the presentinvention generally similar to that shown in Figs. 1 and 2, the samereference numerals being employed to show identical parts. The onlydifference between the furnace Il of Fig. 3 and the furnace III of Figs.l and 2 lies in the fact4 that in the furnace n the end portions of thetubes I1 are fixed in the side walls and are not supported between theside walls. More particularly, collars are attached to the outside ofthe burner tubes Il immediately inside the side walls Il. It will benoted that (similar to the construction shown in Figs. l and 2) theburner tubes Il are formed with an expanded portion 'y or beads llafitting the flaring outer, terminal portion of the -aperture through thevertical side wall receiving the burner tubes I1. Thus, the tubeportions of the burner tubes I1 buried in the side walls of the furnaceare locked therein and held against movement. Therefore, on expansion ofthese portions of the combustion tubes I1 within the coking chamber,said portions are bowed y transversely, as shown in dotted lines in Fig.3. On subsequent cooling, these portions of the burner tubes i1 withinthe coking chamber are straightened out and assume the other positionshown in Fig. 3 in full lines. This bowing and subsequent straighteningof the tubes l1 laids in .the cracking off of adherent coke therefrom.

In Figs. 4, 5, and 6, reference numeral 40 indicates generally anotherfurnace according to the present invention, this furnace beingparticularly adapted for continuous operation. The furnace 40 isgenerally annular in shape and includes pairs of radially spaced steelcolumns 4I eoncentrically erected with respect to a central point, thetops of each pair being joined by radial steel beams 42 from which aresuspended two pairs of concentric spaced channel shaped circular steelbeams I3. From each pair of steel beams 43 are suspended two spacedcircular concentric blocks 44 constructed of suitable refractorymaterial and bil including an upper section supported by the flanges ofthe beams 43 and an intermediate constricted portion of generallytapering or wedge shaped cross section Joined to a, lower section formedwith rabbeted -upper edges for supporting three generally circular,spaced concentric blocks 45 of refractory material having flanges alongtheir upper edges fitting the rabbets of the blocks 44. The blocks M and45 may be cemented together and jointly form the roof of an annularcoking chamber the sides of which are formed by spaced vertical walls ilhaving upper inner beams 4I.

edges twice rabbeted to receive and support the undersides of the outertwo blocks as well as the flanges of said two blocks not supported bythe blocks 44. Further, the roof formed by the blocks Il and l5 as wellas the side walls il are suitably covered by an inner layer 52 and anouter layer Il of insulating material.

The bottom of the coking chamber 5l is formed by a circular rotatablehearth t5 made of suitable refractory material supported by wheels Iirunning on a circular track 51 and suspended from the underside of thehearth bymeans described in detail` hereinbelow. It will be noted thatthe side walls 5I are formed with inward radial projections lila at thebottom thereof while the lower part of the hearth 55 is correspondinglyrecessed, as at 55a, the hearth it being everywhere spaced from the sidewalls 5I for permitting rotation of said hearth. Further, the side walls5I terminate downwardly flush with the bottom of the hearth I5 and havetheir undersides supported by radially extending steel beams Il, havingtheir inner ends resting on vertical steel beams 59 and their outer endsconnected to the The recessed inside of the hearth l5 is covered by asteel sheet B0 projecting below the bottom of the hearth, while theoutside of the hearth is covered by a steel sheet 8| also projectingbelow the bottom of the hearth and having an upper margin Bla extendingradially from the top of the hearth in the plane of the upper surface ofthe hearth into a groove Ma in the inner side wall Si. The downwardlyprojecting portions of the sheets and 6I Vare pierced by spacedapertures 80a and Bib, and have their lower edges bent toward each otherand attached to a circular steel' sheet 02v extending below the hearthwith its margins below the projecting side wall portions Sla foldedupwardly, as at 62a, to define with angle rims 63 depending from theinner lower edges of the sidewalls 5I, two concentric sand traps forsealing off the space beside and below the hearth.

The wheels 5B are supported from the underside of the sheet 62 insuitable brackets 6I carrying journals for the Wheel axles.

Steam can be supplied to the sealed-off space vbelow and beside thehearth 55 through pipes 65 piercing the outer side wall Il. Theapertures Sib and 60a permit flow of steam into the whole space inquestion.

The top of the hearth 55 slopes slightly outwardly and is subdividedinto a number of equal sections by radial partition walls 66 rising to aheight slightly greater than the desired over-all thickness of the layerof coke to be formed on the hearth 55. For discharge of said coke, saidsections, on rotation of the hearth 55, are successively brought inradial alignment with a pusher member 61 supported on steel beams 88inside the innermost side wall 5I of the hearth and adapted to push thecontents of the section aligned therewith out through a radial apertureB9 in the outer side wall 5I discharging into a radially extendinghopper 10 having sloping side walls H at the mouth of the aperture iland adapted to be closed by a vertically operating gate 12. From thehopper l0, the coke is moved by a conveyor 13 into a quenching pit 1I.

For each hearth section between the partition walls 68. except thataligned with the pusher 61, there is provided a tube 'l5 extendingtransversely across the upper part of the coking chamber 50 and adaptedto have a fluid fuel and air blown therethrough for internal heating bycombustion assaa to transmit heat to oil or the like on the hearth 55 byradiation. The tubes 15 are constructed of stainless steel or othermaterial characterized by relatively high heat conductivity andrelatively high coemcient of expansion, for removal of depositedadherent carbon by cooling and subsequent reheating, as describedhereinabove.

A plurality of nozzles 16 pierce the inner side walls of the furnace 40and are so located as to make possible the deposition of oil or the liketo be coked in each section or compartment of the hearth 55 'not alignedradially with the pusher 61. Further, a plurality of conduits 11 throughthe inner side wall of the furnace are similarly arranged for charginggranulated coke or the like into each of said compartments.

The roof of the furnace 40 slopes from a high point where a gas outlet19 is provided for collecting and withdrawing the gases generated duringthe coking process.

In the operation of the furnace illustrated in Figs. 4, 5, and 6, thehearth 55 is intermittently rotated (by means not shown) in acounterclockwise direction to align each hearth compartment successivelywith the pusher 61. When the aligned compartment has been cleared by thepusher 61, and the next, compartment has been aligned with the pusher,granulated or powdered coke is admitted through conduit 11 and spreadover-the floor of the cleared compartment to act as a cleavage planebetween the floor and the coke subsequently formed, Next, the rst chargeof oil or the like to the coke is introduced through conduit 16, and thecharge is coked for a predetermined time in this position by heatsupplied from the stationary burner tubes 15 located near the roof ofthe coking chamber. These tubes are operated in the same manner as thetubes I1 of the furnace of Figs. 1 and 2. The vapors and gases generatedtravel along the roof of the furnace toward the take-up conduit 19through which they are withdrawn from the coking chamber. Thecompartment is then moved to the next position, where additional coke isadded and another charge of oil is added on top of the layer of addedcoke and that formed from the'flrst charge. This process is continueduntil the compartment arrives at a position of alignment with the pusher61 when the coke is pushed oi from the hearth by the pusher or scraperA61 into the hopper to be moved by the conveyor 13 into the quenchingpit 14.

Each section or compartment of the hearth operates in the same manner sothat coke and gaseous solids of uniform quality are producedcontinuously.

If desired, it is possible to omit the addition of further charges whilethe hearth section or compartment travels through the last portion ofthe furnace while continuing ring in the tubes I1 of said furnaceportion to carry the destructive distillation further and to subject thegases and vapors generated to more intensive cracking.

The oil, still residue, tar or the like charged into the furnace forcoking is ordinarily suiilciently viscous, and is at once exposed to acoking temperature, so that the oil, still residue or tar ordinarilydoes not have time to now oil the lower edge of the hearth top beforebeing coked sufficiently to prevent such ow. Further, should such flowoff the lower edge of the hearth top tend to occur, such flow isresisted by the steam admitted into the interspace between the hearth 55and side walls 5I through pipes 6l.

It should be understood that many details of construction and operationmay be varied within a wide range without departing from the principlesof this invention and without sacrificing the advantages mentionedhereinabove and it is therefore not my purpose to limit the patentgranted on this invention otherwise than necessitated by the scope ofthe appended claims.

I claim as my invention:

1. Apparatus for coking organic material comprising means defining acoking chamber adapted to have a, layer of organic material spread overits iloor, and a tube extending through the upper part of said chamberadapted to have fuel burned therein to generate heat to be radiatedontosaid layer of material for coking the same, said tube beingconstructed of austenitic ferrous material characterized by a higherco-efllcient of expansion than carbonaceous material deposited there-,on on cracking of gaseous products of the coking process on contactwith said tube, said tube having its ends anchored in the walls of saidcoking chamber whereby said tube will be bowed when expanded at anelevated temperature so that carbonaceous deposits on said tube aresheared oil when the temperature of said tube is changed.

2. Apparatus for continuously coking organic material comprising spacedconcentric circular side walls, a roof and an annular rotatable hearthbetween said side walls dening in cooperation with said side walls andsaid roof an annular coking chamber, radial partition walls on saidhearth sub-dividing the same into a plurality of sectors, means forintermittently rotating said hearth, pusher means adapted to remove cokeformed in said sectors as said sectors are successively andintermittently aligned with said pusher means, and tube means extendingthrough the upper part of said coking chamber adapted to have fuelburned therein to generate heat to be radiated onto organic materialdeposited on said hearth for coking said material. said tube means beingconstructed of material characterized bya higher coeilcient of expansionthan carbonaceous material deposited thereon on cracking of gaseousproducts of the coking process on contact with said tube means.

V3. Apparatus for coking organic material comprising spaced concentriccircular side walls, a roof, an annular hearth rotatable between saidside walls, means for rotating said hearth intermittently, radialpartition walls subdividing said hearth into a plurality of sectors,pusher means adapted to remove coke from said sectors as each sector issuccessively aligned with said pusher means, conduit means fordepositing liquid material to be -coked on the iloor of each of saidsectors except that sector aligned with said pusher means, means fordepositing coke on the floor of each of said sectors except that sectoraligned with said pusher means, and tube means extending through theupper part of said coking chamber adapted to have fuel burned therein togenerate heat to be radiated onto material deposited in said sectorsexcept that sector aligned with said pusher means, said tube means beingconstructed of material characterized by a higher coefilcient ofexpansion than carbonaceous material deposited thereon on cracking ofgaseous products of the coking process on contact with said tube means.

duit for gaseous products at said high point, an annular hearth betweensaid side walls in spaced relationship thereto and rotatabletherebetween, said hearth sloping outwardly and being subdivided by aplurality of radial partition walls into a plurality of sectors, meansfor intermittently rotating said hearth, a pusher member adapted toremove coke successively from each of said sectors as said sectorssuccessively are aligned with said pusher member on intermittentrotation of said hearth, the side wall opposed to said pusher memberbeing pierced by a discharge aperture through which coke pushed out bysaid pusher member can be discharged, a plurality of conduits fordistributing liquid organic material to be coked in compartments notaligned with said pusher member, a plurality of conduits fordistributing coke in compartments not aligned with said pusher member,sealing means for sealing oi the interspaces between said side walls andsaid hearth at the bottom of said hearth, means for admitting steam intothe interspaces between said side walls and said hearth, a radial flangeprojecting inwardly from said hearth, the inner side wall being formedwith a groove receiving the margin of said ange in spaced relationshipthereto, and a plurality of tubes of austenitic ferrous material withinsaid coking chamber above said hearth for radiating heat generated byinternal combustion in said tubes onto material in said sectors notaligned 10 with said pusher member whereby combustion in said tubes maybe interrupted periodically and air blown therethrough for contractingthe heated tubes to cause shearing off of carbon deposited on said tubesdue to cracking of gaseous products of distillation coming in contactwith said tubes.

LEV A. MEKLER.

REFERENCES CITED The following references are of record in the le oithis patent:

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